Abstract: A refrigerating apparatus enclosing the rivet hoppers of an automatic riveting machine. A refrigerant such as liquid nitrogen is conducted into the refrigerant coils of an insulated enclosure to maintain the temperature of the rivets in the hoppers at sub-zero temperature in order to retard the age hardening process. Frost formation on the rivets is effectively prevented by purging the enclosure with gaseous nitrogen. Upon passing through the coolant coils, the nitrogen absorbs sufficient heat to convert it from the liquid state to a gaseous state. The gas then discharges from the open end of the coils into the enclosure and through a vent in the side wall of the enclosure to atmosphere. To augment frost prevention, dry nitrogen gas is utilized to propel the rivets from the hoppers into the fingers of the riveting machine. Down time for servicing, changing rivets, etc. is reduced to a minimum by a temperature controlled space heater mounted inside the enclosure.